Keystone jack



FIG. 1 is a perspective view of a “keystone jack” showing my new design;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view thereof;

FIG. 4 is a left side view thereof;

FIG. 5 is a right side view thereof;

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom view thereof.

The broken line portion of the figure drawings is included to show unclaimed subject matter only and forms no part of the claimed design. 

CLAIM The ornamental design for a “keystone jack”, as shown and described. 